I don't know, but I think it should be this condition.

Author: cincuranet

Provider/src/FirebirdSql.Data.FirebirdClient/Client/Managed/XdrStream.cs

@@ -361,7 +361,7 @@ public byte[] ReadBytes(byte[] buffer, int count)
 				{
 					toRead -= (currentlyRead = Read(buffer, count - toRead, toRead));
 				}
-				if (toRead == count)
+				if (toRead > 0)
 				{
 					_ioFailed = true;
 					throw new IOException();
@@ -379,7 +379,7 @@ public async Task<byte[]> ReadBytesAsync(byte[] buffer, int count)
 				{
 					toRead -= (currentlyRead = await ReadAsync(buffer, count - toRead, toRead).ConfigureAwait(false));
 				}
-				if (toRead == count)
+				if (toRead > 0)
 				{
 					_ioFailed = true;
 					throw new IOException();